(Meth)acrylic resins containing methyl methacrylate as a main component exhibit excellent transparency, heat resistance, and weather resistance and have well-balanced performance in resin physical properties such as mechanical strength, thermal properties, and molding processability. Hence, they are used in a great number of applications such as lighting materials, optical materials, signboards, displays, decorative members, and building materials, and these applications are required to exhibit flame retardancy and heat resistance.
Hence, investigations have been carried out to impart flame retardancy to (meth)acrylic resin products without impairing transparency, heat resistance, or weather resistance which is a feature of (meth) acrylic resins.
Patent Literature 1 proposes a flame retardant methacrylic resin plate containing a (meth)acrylic polymer containing methyl methacrylate and isobornyl (meth)acrylate and a flame resistant polymeric phosphorus compound.
Patent Literature 2 proposes a flame retardant methacrylic resin plate composed of a methacrylic resin containing a heat resistance improving monomer and a halogenated phosphoric acid ester and discloses dicyclopentanyl (meth)acrylate as the heat resistance improving monomer.